Determination of mercury species in sea-water by liquid chromatography with inductively coupled plasma mass spectrometric detection

Abstract

A liquid chromatographic method coupled with inductively coupled plasma mass spectrometry for the speciation of methylmercury chloride, mercury(II) chloride and ethylmercury chloride in sea-water is described. The three species were eluted from a C₁₈ column (150 × 3.2 mm id) at 260, 340 and 750 s, respectively, with a mobile phase of 1% v/v acetonitrile and 0.005% 2-mercaptoethanol in 0.06 mol l^–1 ammonium acetate pumped at 1.0 ml min^–1. The total mercury determined in TORT-1 Lobster Hepatopancreas (350 ± 62 µg l^–1) was in good agreement with the certified value (330 ± 60 µg l^–1). The detection limits (3s) in artificial sea-water were 0.25 µg l^–1 for methylmercury chloride and mercury(II) chloride and 0.75 µg l^–1 for ethylmercury chloride. Off-line preconcentration using a dithiocarbamate (Dithiochel) resin gave detection limits (signal-to-noise ration = 2) of 16 ng l^–1 for methylmercury chloride and 17 ng l^–1 for mercury(II) chloride using a 50-fold preconcentration factor for a 1 I sample of synthetic sea-water.